class_docstr: Interface for implementing a Trial Scheduler class.
  
  Note to Tune developers: If a new scheduler is added, please update
  `air/_internal/usage.py`.
docstr: Save trial scheduler to a checkpoint
docstr_tok: ["Save","trial","scheduler","to","a","checkpoint"]
code: def save(self, checkpoint_path: str):
      """Save trial scheduler to a checkpoint"""
      raise NotImplementedError
  
imports: from typing import Dict, Optional, TYPE_CHECKING
  from ray.air._internal.usage import tag_scheduler
  from ray.tune.result import DEFAULT_METRIC
  from ray.tune.experiment import Trial
  from ray.util.annotations import DeveloperAPI, PublicAPI
label_desc: Use image node_id 12 for calling the TrialScheduler obj's underlying member method code with example usage: obj.save(checkpoint_path) without return types